US20020180587A1 - Method for communication with multiple transponders - Google Patents

Method for communication with multiple transponders Download PDF

Info

Publication number
US20020180587A1
US20020180587A1 US10090595 US9059502A US2002180587A1 US 20020180587 A1 US20020180587 A1 US 20020180587A1 US 10090595 US10090595 US 10090595 US 9059502 A US9059502 A US 9059502A US 2002180587 A1 US2002180587 A1 US 2002180587A1
Authority
US
Grant status
Application
Patent type
Prior art keywords
information
transponders
method according
interrogator
command
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US10090595
Inventor
Peter Stegmaier
Jean-Marc Jobin
Takamasa Ishii
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Datamars SA
Original Assignee
Datamars SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

Links

Images

Classifications

    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06KRECOGNITION OF DATA; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/0008General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

A method for communication with multiple transponders, particularly for reading digital information from transponders. The information being different in every transponder, as may be a chip serial number (S/N), is transmitted by the transponders using the same response channel for all transponders in such a way that possible states of a digital information per digit are transmitted during different windows in time for every digit position using a type of modulation (e.g. ASK, FSK, PSK). Each window is associated to a possible state of a digit position. In one embodiment some of the windows are associated to a predetermined state corresponding to no modulation for reference.

Description

    FIELD OF THE INVENTION
  • The present invention relates to a method for communication with multiple transponders, particularly for reading digital information from transponders. In the following specification and claims “transponder” means any responding device which may be activated for transmitting information to an interrogating device. [0001]
  • BACKGROUND OF THE INVENTION
  • In many fields of information interchange, the use of one communication channel for multiple transponders is a necessity. Many approaches have been published. [0002]
  • SUMMARY OF THE INVENTION
  • Here we describe a novel approach particularly useful for addressing, reading from, and writing to multiple passive transponders in the interrogating field of an interrogating device. The algorithm can be extended to other configurations as well as to other fields of application. [0003]
  • The algorithm according to the invention makes use of information which differs in every transponder to be communicated to contemporarily. This different information may well be a chip serial number (referred to as S/N), which is used below for the explanation of the principle. [0004]
  • Upon a specific command of the interrogator, all transponders respond with the complete S/N or with a part of it, according to the contents of the command: the command may be e.g. “transmit all S/N or transmit S/N bit 1 to bit 12”. This is done by some modulation scheme as may be ASK, FSK or PSK. [0005]
  • The present invention particularly relates to handling of different bit patterns over the same communication channel for the assessment of the various transponder S/N: By separating the transponder modulation activity for the single information (bits) of the S/N into multiple windows in time per bit position of the S/N, collision of modulations indicating different information is avoided and the interrogator can determine for every bit position whether there are transponders in the field with bit information=0 and/or bit information=1 at the corresponding position. [0006]
  • The interrogator now can use a specific set of commands to have only those transponders respond whose S/N corresponds to a given combination at a given bit position determined by the interrogator using the previous call. This allows the interrogator to completely determine the S/N of every transponder.[0007]
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • The invention will now be explained in detail with reference to the accompanying drawings illustrating a preferred embodiment of the invention. [0008]
  • FIG. 1 shows an example of the digital information e.g. chip S/N to be read from a transponder, [0009]
  • FIG. 2 illustrates a first “slot method” according to the present invention, [0010]
  • FIG. 3 illustrates another “slot method” according to the present invention, [0011]
  • FIG. 4 illustrates an example of reading out and analysis of the digital information from three transponders, and [0012]
  • FIG. 5 is a schematic illustration of the progress of analysis according to FIG. 4.[0013]
  • DESCRIPTION OF THE PREFERRED EMBODIMENT
  • For all following explanations a hypothetical chip serial number (denoted in the following by S/N) is used. Any other information different in all transponders contemporarily in the same interrogator field can also be used. [0014]
  • Modulations shown in the examples are digital, and are able to transmit binary information (i.e. 0 and 1). The present invention is easily expandable to modulations which are able to represent more than 2 levels. [0015]
  • The following example describes the situation of multiple transponders being interrogated by one interrogator being e.g. in the form of a transceiver. Other configurations, i.e. a single transponder being interrogated or multiple interrogators interrogating multiple transponders can also be realized. [0016]
  • All following descriptions are independent of frequencies and field types (electric, magnetic, etc.) used for transponder communication as well as from active or passive transponder implementations. [0017]
  • FIG. 1 shows an example of the digital information comprising 8 bits to be read from a transponder, for instance a chip serial number (S/N). [0018]
  • FIG. 2 illustrates a basic principle of this invention. Upon activation of one ore more transponder(s) within reach of an interrogator, the transponders simultaneously and synchronously retransmit bit information after bit information. [0019]
  • In one embodiment of the present invention the transmission of the information is activated upon request by the interrogator. In a preferred embodiment synchronization of the transmission is achieved by a command issued by the interrogator. [0020]
  • In another preferred embodiment the transponders wait a specified time after power-up for the interrogator to issue a command. If no command is received, the transponders go into a continuous transmission mode transmitting their S/N. [0021]
  • For every bit transmitted, two time slots or windows are provided per bit, for instance bit n as shown in FIG. 2. As shown in FIG. 2, response slot “0” contains modulation of the response signal for information “0”, while response slot “1” contains modulation of the response signal for information “1”. Of course, the response of one determined transponder for bit n may only be “0” or “1”, but FIG. 2 illustrates the principle, and if two or more transponders are activated for answering in synchronism, it may of course arrive, that modulation will be detected for both information or levels “0” and “1” as will be seen later. Thus, detection of modulation in slot “0” indicates the presence of one or more transponders with the binary information “0” at the corresponding position of the S/N, while detection of modulation in slot “1” indicates the presence of one or more transponders with the binary information “1” at the corresponding position of the S/N. Modulation is chosen so that modulating in the same time slot can have deeper but still detectable modulation. [0022]
  • FIG. 3 shows another type of slot method. Response slots “0” and “1” correspond to those illustrated in FIG. 2. A third reference slot for “no modulation” is added. In this way the accuracy of the modulation detection may be enhanced, e.g. for high ambient noise conditions. The reference slot provides the interrogator periodically with a reference signal, which allows a comparison of the signals received in slots “0” and “1” to defined no-modulation conditions. [0023]
  • FIG. 4 illustrates an example of an interrogating sequence assessing the information (S/N) of three transponders, S/N [0024] 1, S/N 2 and S/N 3. As will be seen from FIG. 4 and its text, the interrogator can send specific commands. In a first step a) the command is: “transmit all S/N”. Dark fields in the two time slots associated to each bit indicate at the left “modulation 0” and at the right “modulation 1”. Thus, since all digital information S/N comprise the first bit “1”, the answer received is only “1”, that is, whatever number of transponders have answered, all their answers comprise a first bit “1”. Accordingly, the second bit of the information of each transponder is “0”, this resulting in an information “0” by the dark field in the left slot of bit 1. For bit 2 all answers comprise the value “1”. For bit 3 the information differs for one of the transponders, this resulting in the information that at least two transponders have answered with different values for bit 3. This situation, which also applies for bits 5, 6 and 7, will be called “collision” in the following, and this situation needs specific treatment for assessing the full digital information from all transponders. A first step in this direction is indicated at c) in FIG. 4. The interrogator issues the command to the transponders to only transmit bits 4-7 of the S/N and defines the value of bit 3=0. Since transponder No. 2 only has value “0” in bit 3, this transponder now transmits all remaining bits 4 to 7, whereby the full information from this transponder is available. In a further step e) the transponders are asked to transmit the values of bits 4 to 7 if bit 3 is “1”. This results in other collision situations for bits 6 and 7, and it is evident from FIG. 4, by which method of further approximation the full information from transponders Nos. 1 and 3 is obtained.
  • The interrogator command “transmit S/N, from bit n, if bit n−1=x” as shown in steps c, e, g, h of FIG. 4 may also include all previous bit values in order to avoid misinterpretation if additional transponders enter the interrogating field while the method is executed. [0025]
  • Various strategies can be applied to find the remaining S/N as may be returning to the previous collision and selecting a different transponder by using an appropriate command or returning to the “top” by issuing another “transmit all S/N” command. [0026]
  • FIG. 5 schematically illustrates the steps explained in FIG. 4, for transponders Nos. [0027] 1 to 3. It particularly shows that specific strategies are necessary as soon as collision occurs.
  • One further such strategy, which may be called “split S/N inquiry” works as follows: Upon a specific command of the interrogator during transmission of the S/N by the transponders, all transponders in the interrogating field halt transmission and wait for the next command. This approach can be useful if the time after a collision is to be saved allowing the interrogator to immediately call the respective transponders using a specific preselected value for the bit position at which the collision occurred. It may be advisable to implement this option by one or more short transmission pauses during the transmission of the S/N, e.g. every 8 bits, to allow transponders to listen to such commands issued by the interrogator. [0028]
  • In one embodiment of the method the interrogator can halt transmission of the transponders (mute condition) between any two bit cells by issuing a corresponding command for saving time if e.g. the interrogator determines that the following part of the different information S/N does no longer yield significant information. After entering into the halt or mute condition the transponders wait for the next command. [0029]
  • In another embodiment the transponders can be muted temporarily or permanently by issuing an appropriate command to the last active transponder or by integrating the S/N of the transponder into the command. [0030]
  • Still in another embodiment the transponders wait a specified time after the transmission of the S/N before transmitting the S/N again for allowing the interrogator to issue a command after the first or any subsequent transmission of the S/N. [0031]
  • In a further embodiment the information transmitted by the transponders is protected by some type of checksum, which is e.g. based on a CRC algorithm (“cyclic redundancy check”). If e.g. only one transponder is in the field, the complete S/N is read immediately and checked using the checksum. This avoids further communication with the transponder concerning S/N assessment. Usage of such a checksum results in an increase of data reliability and the corresponding information can be used for further processing e.g. for database access. [0032]
  • Still in a further embodiment the information of known length and different in every transponder, e.g. a unique S/N being of a predetermined number of digits, is complemented by additional bits, as may be header bits for synchronization, stuff-bits and the like, wherein the additional bits are also transmitted by the transponders. [0033]
  • Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims. [0034]
  • Glossary [0035]
    ASK amplitude shift keying
    CRC cyclic redundancy check
    FSK frequency shift keying
    PSK phase shift keying
    S/N serial number

Claims (26)

  1. 1. A method for communication with multiple transponders, particularly for reading digital information from transponders, wherein information being different in every transponder, as may be a chip serial number (S/N), is transmitted by the transponders using the same response channel for all transponders in such a way that possible states of a digital information per digit are transmitted during different windows in time for every digit position using a type of modulation (e.g. ASK, FSK, PSK), each window being associated to a possible state of a digit position, thus allowing the interrogator to assess the existence of the respective information in the transponder population per digit position.
  2. 2. A method according to claim 1, wherein the information has a known length.
  3. 3. A method according to claim 1, wherein the digital information is encoded in the binary system so that each window corresponds to a bit value.
  4. 4. A method according to claim 1, wherein the information is only transmitted upon request by the interrogator.
  5. 5. A method according to claim 1, wherein the information is transmitted in a synchronized way e.g. by a command issued by the interrogator.
  6. 6. A method according to claim 1, wherein with a set of commands, the interrogator is capable of calling to respond or writing to only this/those transponder/s with selected parts of the information being different in every transponder.
  7. 7. A method according to claim 1, wherein the interrogator may halt transmission of the transponders between any two bit cells by issuing a corresponding command for saving time if the interrogator determines that the following part of the different information does no longer yield significant information.
  8. 8. A method according to claim 1, wherein after the transmission of a determined number of information bits the transponders pause modulation for listening to eventual commands issued by the interrogator.
  9. 9. A method according to claim 1, wherein transponders can be muted temporarily or permanently by issuing an appropriate command to the last active transponder or by integrating the information, preferably S/N, of the transponder into the command.
  10. 10. A method according to claim 1, wherein the transponders wait a specified time after power-up for the interrogator to issue a command and wherein the transponders go into a continuous transmission mode transmitting their information, preferably S/N, if no command is received.
  11. 11. A method according to claim 10, wherein the transponders wait a specified time after the transmission of the information, preferably S/N , before transmitting the information again for allowing the interrogator to issue a command after the first or any subsequent transmission of the information.
  12. 12. A method according to claim 1, wherein the information transmitted by the transponders is protected by some type of checksum as may be a CRC algorithm, for increasing data reliability.
  13. 13. A method according to claim 1, wherein the information transmitted by the transponders is complemented by additional bits, preferably not containing information as may be header bits for synchronization, stuff-bits and the like.
  14. 14. A method for communication with multiple transponders, particularly for reading digital information from transponders, wherein information being different in every transponder, as may be a chip serial number (S/N), is transmitted by the transponders using the same response channel for all transponders in such a way that possible states of a digital information per digit are transmitted during different windows in time for every digit position using a type of modulation (e.g. ASK, FSK, PSK), the windows being associated to a possible state of a digit position or to a predetermined state corresponding to no modulation for reference, thus allowing the interrogator to assess the existence of the respective information in the transponder population per digit position.
  15. 15. A method according to claim 14, wherein the information has a known length.
  16. 16. A method according to claim 14, wherein the digital information is encoded in the binary system (e.g. 0, 1) so that the first window corresponds to one value (e.g. 0), the second window corresponds to another bit value (e.g. 1), and the third window corresponds to no modulation for reference.
  17. 17. A method according to claim 14, wherein the information is only transmitted upon request by the interrogator.
  18. 18. A method according to claim 14, wherein the information is transmitted in a synchronized way e.g. by a command issued by the interrogator.
  19. 19. A method according to claim 14, wherein with a set of commands, the interrogator is capable of calling to respond or writing to only this/those transponder/s with selected parts of the information being different in every transponder.
  20. 20. A method according to claim 14, wherein the interrogator may halt transmission of the transponders between any two bit cells by issuing a corresponding command for saving time if the interrogator determines that the following part of the different information does no longer yield significant information.
  21. 21. A method according to claim 14, wherein after the transmission of a determined number of information bits the transponders pause modulation for listening to eventual commands issued by the interrogator.
  22. 22. A method according to claim 14, wherein transponders can be muted temporarily or permanently by issuing an appropriate command to the last active transponder or by integrating the information, preferably S/N, of the transponder into the command.
  23. 23. A method according to claim 14, wherein the transponders wait a specified time after power-up for the interrogator to issue a command and wherein the transponders go into a continuous transmission mode transmitting their information, preferably S/N, if no command is received.
  24. 24. A method according to claim 23, wherein the transponders wait a specified time after the transmission of the information, preferably S/N, before transmitting the information again for allowing the interrogator to issue a command after the first or any subsequent transmission of the information.
  25. 25. A method according to claim 14, wherein the information transmitted by the transponders is protected by some type of checksum as may be a CRC algorithm, for increasing data reliability.
  26. 26. A method according to claim 14, wherein the information transmitted by the transponders is complemented by additional bits, preferably not containing information as may be header bits for synchronization, stuff-bits and the like.
US10090595 2001-03-05 2002-03-01 Method for communication with multiple transponders Abandoned US20020180587A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP01810228.5 2001-03-05
EP01810228 2001-03-05

Publications (1)

Publication Number Publication Date
US20020180587A1 true true US20020180587A1 (en) 2002-12-05

Family

ID=8183776

Family Applications (1)

Application Number Title Priority Date Filing Date
US10090595 Abandoned US20020180587A1 (en) 2001-03-05 2002-03-01 Method for communication with multiple transponders

Country Status (2)

Country Link
US (1) US20020180587A1 (en)
JP (1) JP2002314456A (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050099298A1 (en) * 2003-11-10 2005-05-12 Mercer Thomas C. Algorithm for RFID security
US20060125598A1 (en) * 2004-12-13 2006-06-15 Atmel Germany Gmbh Method for wireless data transmission
US20060273881A1 (en) * 2005-06-01 2006-12-07 Samsung Electronics Co., Ltd. Identification anti-collision method and radio frequency identification system using the same
US20070075836A1 (en) * 2003-11-10 2007-04-05 3M Innovative Properties Company System for detecting radio-frequency identification tags
EP1914660A1 (en) * 2006-10-19 2008-04-23 Research and Industrial Cooperation Group Query tree based tag identification method in RFID systems
US20100045434A1 (en) * 2005-01-31 2010-02-25 Nxp B.V. Communication between a communication station and data carriers
US20120092136A1 (en) * 2009-06-10 2012-04-19 Zte Corporation Radio frequency identification system and tag counting ending method for anti-collision thereof
EP2149202A4 (en) * 2007-05-23 2015-05-13 Sk Telecom Co Ltd Method for determining optimal frame size for tag collision prevention in rfid system

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5425032A (en) * 1992-04-07 1995-06-13 Hughes Aircraft Company TDMA network and protocol for reader-transponder communications and method
US6456191B1 (en) * 1999-03-23 2002-09-24 Exi Wireless Systems Inc. Tag system with anti-collision features
US6535109B1 (en) * 1998-12-01 2003-03-18 Texas Instruments Sensors And Controls, Inc. System and method for communicating with multiple transponders
US6661336B1 (en) * 1997-05-14 2003-12-09 Btg International Limited Enhanced identification system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5425032A (en) * 1992-04-07 1995-06-13 Hughes Aircraft Company TDMA network and protocol for reader-transponder communications and method
US6661336B1 (en) * 1997-05-14 2003-12-09 Btg International Limited Enhanced identification system
US6535109B1 (en) * 1998-12-01 2003-03-18 Texas Instruments Sensors And Controls, Inc. System and method for communicating with multiple transponders
US6456191B1 (en) * 1999-03-23 2002-09-24 Exi Wireless Systems Inc. Tag system with anti-collision features

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070075836A1 (en) * 2003-11-10 2007-04-05 3M Innovative Properties Company System for detecting radio-frequency identification tags
US7405663B2 (en) 2003-11-10 2008-07-29 3M Innovative Properties Company System for detecting radio-frequency identification tags
US7372364B2 (en) * 2003-11-10 2008-05-13 3M Innovative Properties Company Algorithm for RFID security
US20050099298A1 (en) * 2003-11-10 2005-05-12 Mercer Thomas C. Algorithm for RFID security
US8013716B2 (en) * 2004-12-13 2011-09-06 Atmel Corporation Method for wireless data transmission
US20060125598A1 (en) * 2004-12-13 2006-06-15 Atmel Germany Gmbh Method for wireless data transmission
US20100045434A1 (en) * 2005-01-31 2010-02-25 Nxp B.V. Communication between a communication station and data carriers
US20060273881A1 (en) * 2005-06-01 2006-12-07 Samsung Electronics Co., Ltd. Identification anti-collision method and radio frequency identification system using the same
US8310342B2 (en) * 2005-06-01 2012-11-13 Samsung Electronics Co., Ltd. Identification anti-collision method and radio frequency identification system using the same
US20080106383A1 (en) * 2006-10-19 2008-05-08 Research And Industrial Cooperation Group Query tree based tag identification method in RFID systems
US7612672B2 (en) 2006-10-19 2009-11-03 Research And Industrial Cooperation Group Query tree based tag identification method in RFID systems
EP1914660A1 (en) * 2006-10-19 2008-04-23 Research and Industrial Cooperation Group Query tree based tag identification method in RFID systems
EP2149202A4 (en) * 2007-05-23 2015-05-13 Sk Telecom Co Ltd Method for determining optimal frame size for tag collision prevention in rfid system
US20120092136A1 (en) * 2009-06-10 2012-04-19 Zte Corporation Radio frequency identification system and tag counting ending method for anti-collision thereof
US8653947B2 (en) * 2009-06-10 2014-02-18 Zte Corporation Radio frequency identification system and tag counting ending method for anti-collision thereof

Also Published As

Publication number Publication date Type
JP2002314456A (en) 2002-10-25 application

Similar Documents

Publication Publication Date Title
US5479416A (en) Apparatus and method for error detection and correction in radio frequency identification device
US5696911A (en) Arrangement for eliminating malfunction and/or permitting high-speed transmission in a serial bus connection, and transmitter and receiver units linked to the latter
US4852091A (en) High capacity communication system utilizing OR-type channels
US5929801A (en) Method for repeating interrogations until failing to receive unintelligible responses to identify plurality of transponders by an interrogator
EP0702323A2 (en) System and method for radio frequency tag group select
US6535109B1 (en) System and method for communicating with multiple transponders
US4217588A (en) Object monitoring method and apparatus
EP0768540A1 (en) Transponder system and method
US7009495B2 (en) System and method to identify multiple RFID tags
US5434572A (en) System and method for initiating communications between a controller and a selected subset of multiple transponders in a common RF field
US6265962B1 (en) Method for resolving signal collisions between multiple RFID transponders in a field
US20040135674A1 (en) Method for the efficient reading of a population of radio frequency identification tags with unique identification numbers over a noisy air channel
EP0696011A2 (en) Apparatus and method for identifying multiple transponders
US6538563B1 (en) RF transponder identification system and protocol
US7356041B2 (en) Method and system for transmitting signals using frequency hopping
US20050083179A1 (en) Phase modulation in RF tag
US20050057368A1 (en) Continuous wave (CW) - fixed multiple frequency triggered, radio frequency identification (RFID) tag and system and method employing same
US6559754B1 (en) System for the transmission of data from a data carrier to a station by means of one or at least one other auxiliary carrier signal
US4525713A (en) Electronic tag identification system
US5774459A (en) Method of managing the transmission of messages from a set of transmitters to a single receiver on a single channel
US5649296A (en) Full duplex modulated backscatter system
US5734326A (en) Recognition tag for use in a system for identifying distant items
US20040066279A1 (en) RFID system and method including tag ID compression
US5940006A (en) Enhanced uplink modulated backscatter system
US7672260B2 (en) Method of addressing messages and communications system

Legal Events

Date Code Title Description
AS Assignment

Owner name: DATAMARS SA, SWITZERLAND

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:STEGMAIER, PETER;JOBIN, JEAN-MARC;ISHII, TAKAMASA;REEL/FRAME:012922/0192;SIGNING DATES FROM 20020424 TO 20020428